Control device for reciprocating working pistons



.3mm. I}, 1939. v OJBALLER'i' CONTROL DEVICE FOR RECIPROCATING WQRKING PISTONS Filed March 6, 1957 I 2 sheets-Sheet 1 3 .Zzvehkr- I I 0T7? BALLERT Attorne Jan. 3, 1939. B LLE 2,142,628

CONTROL DEVICE FOR RECIPROCATING WORKING PISTONS Filed March 6, 1937 2 Sheets-Sheet 2 v I Jwmiofi UTTOBALLERT I 3! WW Attorney.

Patented Jan. 3, 19 39 PATENT OFFICE CONTROL DEVICE FOR RECIPROGATING WORKING PISTONS Otto Ballert, Berlin, Germany Application Mai-en s, 1931, Serial No. 129,308 In Germany September 10, 1935 4 Claims. (01. 121-465) active areas of the cylinder chambers corre- The invention relates to a hydraulic difierential piston drive in which cyclically three difierent kinds of movement are produced by connecting first both chambers simultaneously of the hydraulic differential motor with a source of pressure, then only a first one of said chambers with said source and the other with the exhaust, and finally said first mentioned chamber with the exhaust and said second mentioned chamber with said source.

It is known to operate such drives by means of a single source of pressure and to control them by means of a single external control member, a hand lever or the like.

Usually the hydraulic control members for such drives are rotary cocks or slidable piston valves.

These known drives give good results in machine tools or similar devices using relatively low hydraulic pressures but have been found very unsatisfactory for hydraulic presses using pressures which may be up to six times higher.

Such high pressures can be controlled satisfactorily only by poppet valves as is well known in the art. Using such valves, however, it is dimcult to obtain the above mentioned three different working conditions in a simple manner hecause a poppet valve in distinction from a rotary or sliding valve has only two operative positions 1. e. the seated and the unseated position. Consequently for hydraulic presses of this type it is usual to employ separate sources for high and low pressures and to control them by means of four or more separative valves. The present invention makes -it possible to obtain said three difierent kinds of function in hydraulic presses and similar high pressure devices by means of a differential piston motor supplied by only one source of pressure and controlled by only one external controlling member by means of a relatively simple poppet valve control using only two double poppet valves. This is achieved by a system of ,valve chambers interconnected in a peculiar way with one another and with pressure and exhaust respectively and by a peculiar drive for said two double poppet valves making possible a certain movement of the one relative to and independent of the other.

. An embodiment of the invention is illustrated by way of example in the accompanying drawings.

Figs. 1 to '3' show schematically the control devices according to the invention in three different positions, and Figs. la, 2a, 3a showthe sponding to said three positions.

Fig. 4 is anelevational view on an enlarged scale, showing the control devices and particularly the means for actuating same.

Fig. 5 is a section on the line V-V of Fig. 4.

Fig. -6 shows another constructional form of the device for actuating one of the double valves.

P'denotes the pressure generating device and B the outlet container. In the cylinder I a pressure piston 2 is arranged, to which the piston rod 3 is attached. The control devices are located in a casing 4 and consist chiefly of two double valves 5 and 6. In connection with the valve 5 an inlet chamber 1, an outlet chamber 9 and a distribution chamber II are arranged. In similar manner an inlet chamber 8, an outlet chamber i0 and a distribution chamber H are provided for the valve- 6. The valve cone l3 of the control valve 5 is adapted to close off the inlet or pressure chamber 1 from the distribution chamber ll, whereas the valve cone l4 of the same valve is adapted to close oil? the outlet chamber 9 from the distribution chamber l I. The valve cones l5 and ll; of the double control valves 6 are correspondingly arranged. The double valve 5 serves for the control of the stroke chamber ll of the pressure piston, which chamber through the con-5 duit I8 is connected with the distribution chamber II. The double valve 6 serves for controlling the stroke chamber 24, which is connected with the distribution chamber I! through the conduit l9.

The supply or inlet chambers I and 8 are connected with each other through the conduit 20 and with the pressure generator P through the conduit 2|. The conduit 22 provides a communication between the outlet chambers 8 and III, which are connected with the outlet container B through the conduit 23.

The return movement of the working piston is caused, inthe manner indicated in .Fig. 3 by moving the double valve 5 downward, so that the distribution chamber l I is closed by the valve chamber l2 and the conduit is to the annular chamber 24 below the piston,'whilst the fluid in the chamber l1 above the piston flows through the conduit l8, the distributor chamber 1 I, the

outlet chamber 9 and the conduit 28 into the container B. The pressure fluid thus acts upon the piston 2 in the annular pressure chamber 24 in such a manner, that the piston returns with relatively high velocity, hereby developing only little iorce.

As indicated in Fig. 1, at the commencement of the working stroke of the pressure piston 2 the double valve 5 is moved upward, whilst the valve 8 does not move. Through this movement of the valve 5 a communication is created between the pressure generator I and the pressure chamber l1 through the conduit 2|, the inlet chamber 1, the distribution chamber I I and the conduit I8. The annular-stroke chamber 24 and the stroke chamber i1 are thus both receiving pressure fluid, so that the piston 2 is influenced by a force corresponding to the difierence between the cross-sectional areas of the bottom and top sides of the piston 2. This difference is shown by the circle 3 in Fig. 1a. At the commencement of the working stroke the piston 2 is advanced with high velocity and hereby develops relatively little power.

As will be seen from Fig. 2, at the end ot the working stroke oi. the pressure piston the double valve 8 is moved downwardly, so that the valve cone I5 is pressed against its seat and the valve cone it leaves its seat. The communication between the pressure generator and the stroke chamber I1 is maintained and a communication between the stroke chamber 24 and the outlet container B is established over the conduit IS, the distribution chamber l2, the outlet chamber ID, the conduit 22, the outlet chamber 9 and the conduit 23. The piston 2 is therefore influenced by a relatively great force corresponding to the large cross-sectional area l1 (Fig. 2a) of the chamber i1.

Fig. 3a shows the area 24' of the cross section of the smaller cylinder chamber 24 active during the rapid return stroke.-

By suitable selection of the diameter of the pressure piston and the piston rod, the working pressures-and the stroke velocities may be adjusted after the requirements of the materials to be treated.

with reference to Figs. 4 and 5 the double valves 5, 8 are in one direction moved each by a spring 25 or 28 respectively and in the other direction by a bell crank lever 21, which is operatively actuated by a hand lever 28.v One leg 88 of the bell crank lever. 21 contacts with a collar 28 or the like, which is slidable on the stem 01' the double valve 5, and the movement of which in one direction is limited by a stop 80 and in the other direction by a spring 8i.

The double valve 6 is moved by a bell crank lever 82, which is arranged on the casing 4 of the control device. One leg 83 o! the bell crank lever 82 contacts with the stem oi. the valve 8 and its other leg 84 is by means of a rod connected to the leg 88 or the bell crank lever 21. The rod 35 is slidable in a bore in the leg 88 and carries a stationary stop 81.-

Flg. 4 shows the valves in the same position as in Fig. 3.

when the lever 28 is depressed, the double valve 5 is raised, so that the valve cone I8 is lifted from its seat and the valve cone I4 is pressed against its seat. The valve 8 remains in the position shown in the drawings. The positions of the valves thus correspond to those indicated in Fig.

By further depression or the lever 28 the head or the member 85 of the bell crank lever 21 is pressed against the stop 31, whereby, through the members 85, 34, 83, the double valve 6 is moved downwardly. Through this movement the collar 29 is by means or the leg 88 moved along the axis of the valve stem 5 against the resistance of the spring 3!. In this way the parts are brought into the positions shown in Fig. 2.

In the described embodiment it is only necessary to move the valve 5 in one direction by means 01 the hand lever 28. The return movement takes place automatically under the influence of the spring 25.

Fig. 6 illustrates a modified structure of valve operation and shows the valves in the same position as in Fig. 2. The top chamber l1 communicates with the pressure generator and the bottom chamber 24 with the outlet container, and

the pressure piston moves at lowest velocity but exerts the maximum force. The upper end of the double valve 6 forms a piston adapted to cooperate with a cylinder 40, which for instance by means of screws is fixed to the casing 4. The upper end of the piston-like extension of the valve 8 together with the cylinder forms a working chamber, which through the conduit 39 communicates with the space which is under the influence of the pressure fluid. In this case the conduit 39 for instance leads to the inlet chamber 8. When the pressure of the pump increases, the force acting upon the extension of the valve 8 is augmented in such a manner, that progressively of the stroke chamber 24 is shut off from the fluid inlet and brought into communication with the outlet container.

I claim:- I

1. A pressure fluid drive particularly for presses, comprising in combination a source of pressure, a cylinder, a piston in said cylinder, a piston rod connected with said piston, said piston dividing said cylinder into a narrower chamber traversed by said piston rod and a wider chamber free of said rod, a valve housing, in said housing two inlet chambers, two distribution chambers and two outlet chambers, these chambers being arranged in two groups of three chambers each, a connection channel between said inlet chambers, a connection channel between said outlet chambers, a conduit between one of said inlet chambers and said source of pressure, an outlet pipe connected with one of said outlet chambers, a conduit connecting one of said distribution chambers with' said wider chamber, a conduit connecting the other of said distribution chambers with said narrower chamber, in said housing valve seats at opposite ends of each distribution chamber, two twin poppet valves coordinated each to one or said groups of chambers and adapted to cooperate with said seats, one twin valve with one distribution chamber each, each twin valve consisting of an inlet valve head and'an'outlet valve head rigidly connected and separated by a distance greater than the distance between the seats of their distribution chamber, said inlet valve head adapted to control communication between the inlet chamber and the distribution chamber of the coordinated group of chambers, and said outlet valve head adapted 7 spring for each of said twin valves,

to control communication between the outlet chamber and the distribution chamber of the coordinated group of chambers, a' single external control member outside of said casing, a loading said twin valves being impositively coupled in such a degree that after the-inlet valve head of one thereof has been closed the other thereof may be moved independently, and said twin valves being adapted to be moved into three difierent relative control positions, in the first of which positions each distribution chamber is connected with the coordinated inlet chamber and separated from the coordinated outlet chamber, in the second of which positions one distribution chamber is connected with the coordinated inlet chamber but separated from the coordinated outlet chamber whereas the other distribution chamber is separated from the coordinated inlet chamber and connected with the coordinated outlet chamber, and in the third of which positions the relative situation of said twin valves is the reverse one compared withsaid second position.

2. A drive as in claim 1, comprising further a stop on one of said twin valves, a motion transmitting member adapted to slide relative to one of said twin valves in one direction and to abut against said stop in the opposite direction, a spring tending to press said motion transmitting member against said stop, a lost motion connection between said valves, said control member adapted to act upon said motion transmitting member.

3. A drive as in claim 1 comprising further,

a stop on one of said twin valves, a motion transmitting member adapted to slide relative to one of said twin valves in one direction and to abut against said stop in the opposite direction, two elbow levers each of which is coordinated to and in engagement with one of said twin valves, a connecting rod pivoted to one of said elbow levers,-and passing slidably through the other of said elbow levers, and a stop on said rod at the outside of said first mentioned elbow lever.

4. A drive as in claim 1 comprising further an auxiliary hydraulic cylinder secured to said valve housing, a piston secured to one of said twin valves and projecting into said auxiliary cylinder,

a-conduit connecting the free end of said auxiliary cylinder with one of said inlet chambers, said external control member being coupled with the other of said twin valves, said twin valves 2 being mechanically independent from each other.

' O'I'I'O BA LLERT. 

